Strabismus and Ocular Motility Flashcards
What all does the superior rectus muscle do?
elevates (primary action), adducts and intorts
What all does the inferior rectus muscle do?
depresses, adducts and excyclotort
WHat does the inferior oblique do?
elevates and extorts
What is duction?
movement of one eye
What is version?
movement of both eyes (conjugate)
What is vergences?
disconjugate movement of eyes
What is strabismus?
misalignment of visual axes
What is phoria?
latent deviation that appears only when fusion is disrupted
sometimes deviated
What is tropia?
manifest deviation, beyond the range of fusional control
always deviated
What can you use the corneal light reflex for>
to determine if the eye is deviated in a particular direction based on where the light reflex shows up
How can you determine if someone has a tropia?
use cover-uncover test and if eye deviates with covering then you have a tropia
How can you tell if someone has phoria?
use the cross cover test. You do the cover uncover test and nothing happens but when you cover one eye and then cross horizontally to the other eye, the eye deviates which lets you know that the deviation is there only SOME of the time, thus it is a phoria.i.e when you break fusioN!
What is esotropia?
nasalward deviation of eye “crossed eye”
What is exotropia?
temporal deviation “wall eyed”
What is hypertropia?
vertical deviation, relative to higher eye
What is this:
angle of devation remains constant regardless of direction of gaze, range of motion of eyes is full, wihout limitations or restrictions.
When is this most commonly seen?
concomitant deviation
in childhood onset strabismus
What is this:
Angle of strabismus varies with gaze diraction; limitation of ocular movements. Patient may exhibit abnormal head posture to maintain binocularity.
Is this congenital or acquired?
incomitant deviation
may be congenital or acquired
How do you get comitant deviations?
abnormalities of binocularity, motion processing, poor fusional vergences
How do you et incomitant deviations?
developmental (Duanes, Browns), neurological (cranial nerve palsy, myasthenia), restrictive (trauma, thyroid disease)
How do you measure the angle of deviation?
with prisms
What does the motility evaluation test?
ductions and versions
What does sensory testing check out?
assess binocularity
What are the different kinds of comitant strabismus (4)?
pseudoesotropia
congenital esotropia
accomodative esotropia
exotropia
What is this:
wide flat nasal bridge and epicanthal folds, normal alignment by light reflex and cover tests.
pseudoestropia
common in infants
What is this:
large angle deviation, cross fixation, limitation of abduction may be confused with congenital 6th nerve palsy, usually requires surgical treatment
congenital esotropia
What is this:
over-convergence related to accomodation in hyperopia, usual age of onset 2-3 years, usually treated with glasses, bifocals sometimes necessary
accomodative esotropia
What is this:
Usually intermittent in childhood; normal binocular function when eyes straight; eyes deviate with fatigue or inattention
exotropia
What are the three developmental incomitant stabismus?
Duanes’ retraction syndrome
Mobius Syndrome
Brown’s Syndrome
What is this:
absence of 6th nerve nucleus resulting in deficient abduction, miswiring of third nerve result in cocontraction of medial rectus and lateral rectus with globe retraction on adduction.
Duane’s Retraction Syndrome
What is mobius syndrome?
congenital bilateral 6th and 7th nerve palsies
What is brown’s syndrome?
abnormality of trochlear pulley, congenital or acquired, deficit of elevation of eye in adduction
What are the three types of restrictive strabismus?
congenital fibrosis syndrome
grave’s disease
orbital fractures
What can cause this:
autosomal dominant, inelastic muscles and ptosis, positive forced ductions.
congenital fibrosis syndrome
What can cause this:
lymphocytic infiltration and secondary fibrosis of extraocular muscles in thyroid disease, enlargement of muscles may cause compression of optic nerves and vision loss, IR and MR most commonly affected
graves’ disease
What can orbital fractures cause?
scarring/entrapment of orbital tissue/extraocular muscles
What are the five ways you can get neurologic strabismus?
cranial nerve palsies third nerve palsy fourth nerve palsy sixth nerve palsy myasthenia gravis
What will cause cranial nerve palsies?
microvascular problems, tumor, trauma, aneurysm.
What happens if you have third nerve palsy?
your eye is down and out Ptosis pupillary involvement (dilation)
What happens if you have fourth nerve palsy?
oblique diplopia and torsion, bilateral often secondary to trauma (nasal upshoot)
What happens if you have 6th nerve palsy?
abduction deficit, face turn to affected side (one eye looks cross eyed)
WHat happens with myasthenia gravis?
Why?
What happens when the patient gets tired?
variable strabismus and ptosis
because of acetycholine antibodies that cause muscle weakness
it gets worse
How do you test for myasthenia gravis?
tensilon test
What are the three types of strabismus surgery?
recession
resection
transposition
What surgery will weaken the effect of the muscle operated on?
recession
What surgery will enhance the effect of the muscle operated on?
resection
What surgery will shift force vectors of muscle?
transposition
What is binocular vision?
fusion of images from both eyes
What is sterposis?
high grade of fusion that gives depth
